During fluid therapies such as hemodialysis, hemofiltration, hemodiafiltration and peritoneal dialysis, the dialysate pH and buffer concentration can play a critical role in patient outcomes. The dialysate pH and buffer concentration are prescribed for a patient based on the acid-base status of the patient. Acidotic patients can be treated by increasing their bicarbonate buffer levels in the dialysate and patients with alkalosis can be treated by decreasing their bicarbonate levels in the dialysate. A method to measure pH and buffer dialysate concentration is especially important with systems that contain a component that may change the pH level and bicarbonate concentration to unknown values. For example, regenerative hemodialysis systems, such as the Recirculating Dialysate System (“REDY” System), contain sorbent materials that release and/or remove hydrogen ions and bicarbonate from the dialysate fluid. The removal and/or addition of hydrogen ions and bicarbonate to the dialysate fluid depend on several factors including: patient blood urea level, patient weight, dialysate composition, sorbent properties, etc. Because of this, it becomes difficult to predict the changes in dialysate pH and bicarbonate concentration that will occur during a hemodialysis session. Therefore, there is a need for systems and methods that can measure the pH and bicarbonate concentration of the dialysate.